1. Field of the Invention
The present invention relates to a method and an apparatus for separating and removing an image forming substance from an image holding member onto which the image forming substance is stably attached by an image forming apparatus such as a copying machine, a facsimile telegraph, a printer, etc.
2. Description of the Related Art
There are generally various kinds of known methods and apparatuses for removing an image forming substance such as toner from a sheet of paper as a recorded image holding member. For example, Japanese Patent Application Laying Open (KOKAI) No. 1-101578 shows an image forming substance removing method using a solvent. In this image forming substance removing method, a sheet of paper attaching toner thereon is dipped into a soluble solvent of toner resin and a supersonic wave is vibrated in this paper sheet so that the toner dissolved into the solvent is separated from a paper face. Japanese Patent Application Laying Open (KOKAI) No. 4-300395 shows another image forming substance removing method. In this method, a solvent is attached to a printed sheet portion of used paper by a method of dipping, spraying or coating, etc. so that toner is dissolved. The dissolved toner is removed from the paper sheet by a method of cleaning, air suction, absorbent contact, mechanical separation or electrostatic absorption, etc.
For example, Japanese Patent Application Laying Open (KOKAI) No. 2 -255195 shows an image forming substance removing method in which no solvent is used. In this method, thermally melted ink or toner is attached by an electrophotographic system or a thermal transfer system onto a printing member in which a supporting member is coated with a mold releasing agent. An ink separating member is overlapped with the printing member and these members are transmitted between a heating roller and a pressure roller. The ink separating member is separated from the printing member after the ink separating member is cooled. Thus, the ink or toner is attached onto the ink separating member so that the ink or toner is removed from the printing member. Japanese Patent Application Laying Open (KOKAI) No. 4-64472 shows an eraser comprising at least an endless sheet having thermally melted resin on its surface, a heating roller and a cooling roller for supporting and rotating the endless sheet, a pressing roller for pressing a sheet of erasable paper moldreleased on its surface against thermally softened or melted resin, and a driving section for operating these members in association with each other. Japanese Patent Application Laying Open (KOKAI) No. 4-82983 shows an image forming substance removing apparatus comprising two parallel rollers coming in press contact with each other and rotated to pass a paper sheet through a press contact portion, a heater for heating at least one of these two Pollers, a scraper for separating the paper sheet passing through the press contact portion from these rollers, and a separator for removing an image forming substance attached onto these rollers therefrom.
Each of the above methods and apparatuses using no solvent is used to remove the image forming substance from the recorded image holding member in which an image is recorded on a sheet of normal paper having paper fibers exposed onto a paper surface. In this case, for example, the image forming substance having thermally melted resin as a principal component is melted and attached onto the image holding member in a fixing process in the electrophotographic system. Accordingly, the image forming substance is strongly fixed to paper fibers on a surface of the image holding member. Therefore, when the image forming substance is removed, paper fibers on the image, holding member surface are removed therefrom together with the image forming substance so that the image holding member is damaged and a paper quality is reduced. In particular, when the image holding member is heated and pressurized through the above ink separating member, the endless sheet or the above rollers to improve removal of the image forming substance, a fixing property between the image forming substance and the image holding member is conversely increased in various kinds of conditions so that it is difficult to remove the image forming substance from the image holding member.
For example, the inventors in this patent application proposed an image forming substance removing method in Japanese Patent Application No. 4-255916. In this method, at least one kind of water or aqueous solution is selected from a group of water as an unstabilizing agent, an aqueous solution including a surfactant, an aqueous solution including a water-soluble polymer, and an aqueous solution including a surfactant and a water-soluble polymer. This selected water or aqueous solution is held in a recorded image holding member. An image forming substance is heated and adhered to a separating member. Otherwise, the image forming substance is pressurized and adhered to the separating member. The image forming substance is separated from the image holding member through the separating member. In this method, only the image forming substance can be removed from the image holding member without relatively damaging a paper quality of the image holding member.
In the above general image forming substance removing method and apparatus, the unstabilizing liquid is provided to the image holding member and the image forming substance is separated from the image holding member in the image forming substance removing processing. When the image holding member is repeatedly used by this image forming substance removing processing, there is a fear of damaging the image holding member when the number of repetitions of the image forming substance removing processing is increased. The inventors of this patent application confirmed as a fact that the damage of the image holding member gradually becomes serious in accordance with the number of repetitions of the image forming substance removing processing so that no image holding member can be reused. When the image holding member is repeatedly used by the image forming substance removing processing, there is a fear of changing an optimum process condition of the image forming substance removal to the image holding member by hysteresis of the image forming substance removing processing. For example, there is a fear of changing a process condition in which the damage of the image holding member is minimized and the image forming substance can be completely removed from the image holding member.